1. Field of the Invention
The present invention relates to a method for connecting a bus bar of a capacitor, capable of improving temperature characteristics and reliability of the capacitor by reducing inductance when attaching the bus bar on a sprayed surface of a capacitor device, thereby reducing impedance of the capacitor such that heat generation can be restrained during use of the capacitor, and a product fabricated by the same.
2. Description of the Related Art
In general, electric equipment capacitor devices, phase-advanced capacitor devices and electronic equipment capacitor devices are used in a variety of industrial fields.
In the capacitor device, a plastic film such as polyethylene terephthalate resin, polypropylene resin, polyethylene naphthalate resin, polycarbonate resin and the like is used as a dielectric. The capacitor device is fabricated by winding a vapor-deposited metal film on either or both sides of the plastic film, and forming a polar plate (hereinafter, referred to as “sprayed surface”) on both sides of the wound vapor-deposited film by spraying Zn, Zn alloy, tin, or Zn firstly and tin secondarily. Here, the sprayed surfaces of the capacitor fabricated by the vapor-deposited film do not have discrimination of polarities.
Since the capacitors have different capacitance in accordance with their usages, the capacitors are fabricated to have the predetermined capacitance by increasing and decreasing the number of capacitor devices. When fabricating a large-capacitance capacitor, bus bars are connected to the capacitor devices.
More specifically, in the capacitor comprising a number of the capacitor devices, a pair of bus bars are connected to the sprayed surfaces disposed at both sides of each capacitor device by soldering. In addition, a cable connection terminal is bonded to the bus bar.
As shown in FIGS. 1A and 1B, the capacitors including the pair of bus bars 1 and 2 attached thereto are received in an outer case 6 such as a plastic case or a metal case. Next, the outer case 6 is charged with an insulating material including epoxy, urethane and the like, and the insulating material is cured in the outer case 6. Thus, fabrication of the capacitor is completed. The sprayed surfaces of the capacitor device 3 may be arranged horizontally or vertically as intended by a manufacturer.
The capacitor device 3 and the pair of bus bars 1 and 2 are fixed to each other by curing of the insulating material. Only the terminals 4 attached to the bus bars 1 and 2 are exposed to the outside of the outer case 6, thereby constituting a polar device which is connected with a power cable.
However, when the voltage or current being applied is high, heat generates at the capacitor device 3. Such heat deteriorates electric characteristics, lifespan and reliability of the capacitor.
The above problems are caused by inductance generated from various component parts of the capacitor.
The assembling process and structure of a conventional capacitor will now be described.
As shown in FIG. 1A, in the conventional capacitor device 3, when the pair of bus bars 1 and 2 are attached to the sprayed surfaces 5 of the capacitor device 3, to be insulated from each other, any one of the bus bars 1 and 2 is connected to one sprayed surface and the other one is connected to the other sprayed surface, thereby forming a serial connection.
However, although variations in the structure of the serial bus bar were applied as shown in FIGS. 1A, 2A and 3A, more specifically, by varying thickness and width of the bus bar and the interval between the bus bars, such structural changes did not influence a degree of the impedance. Also, there happened no noticeable change regarding the effect.